CN114963691A - Low pressure CO 2 Low-temperature gas separation method and device - Google Patents
Low pressure CO 2 Low-temperature gas separation method and device Download PDFInfo
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- CN114963691A CN114963691A CN202210610116.1A CN202210610116A CN114963691A CN 114963691 A CN114963691 A CN 114963691A CN 202210610116 A CN202210610116 A CN 202210610116A CN 114963691 A CN114963691 A CN 114963691A
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- 238000000926 separation method Methods 0.000 title claims abstract description 24
- 239000002994 raw material Substances 0.000 claims abstract description 50
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims abstract description 43
- 238000009833 condensation Methods 0.000 claims abstract description 25
- 230000005494 condensation Effects 0.000 claims abstract description 25
- 229910021529 ammonia Inorganic materials 0.000 claims abstract description 17
- 238000000746 purification Methods 0.000 claims abstract description 9
- 230000006835 compression Effects 0.000 claims abstract description 7
- 238000007906 compression Methods 0.000 claims abstract description 7
- 238000001816 cooling Methods 0.000 claims abstract description 7
- 238000004064 recycling Methods 0.000 claims abstract description 5
- 239000007789 gas Substances 0.000 claims description 173
- 238000011084 recovery Methods 0.000 claims description 17
- 239000007788 liquid Substances 0.000 claims description 12
- 239000007791 liquid phase Substances 0.000 claims description 9
- 239000012071 phase Substances 0.000 claims description 9
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 9
- 239000004215 Carbon black (E152) Substances 0.000 claims description 6
- 239000002737 fuel gas Substances 0.000 claims description 6
- 229930195733 hydrocarbon Natural products 0.000 claims description 6
- 150000002430 hydrocarbons Chemical class 0.000 claims description 6
- IGEZMQWPBDNNPS-UHFFFAOYSA-N B.CO Chemical compound B.CO IGEZMQWPBDNNPS-UHFFFAOYSA-N 0.000 claims description 3
- 239000000446 fuel Substances 0.000 claims description 3
- 239000000463 material Substances 0.000 claims description 3
- 239000002918 waste heat Substances 0.000 claims description 3
- 238000005265 energy consumption Methods 0.000 abstract description 11
- 238000000034 method Methods 0.000 abstract description 6
- 238000010992 reflux Methods 0.000 abstract description 3
- 238000005516 engineering process Methods 0.000 description 6
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 3
- 230000008901 benefit Effects 0.000 description 3
- 229910052799 carbon Inorganic materials 0.000 description 3
- 125000004122 cyclic group Chemical group 0.000 description 3
- 239000002803 fossil fuel Substances 0.000 description 3
- 230000000694 effects Effects 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 230000009919 sequestration Effects 0.000 description 1
- 239000006200 vaporizer Substances 0.000 description 1
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
- F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
- F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
- F25J3/0228—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream
- F25J3/0266—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream separation of carbon dioxide
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B32/00—Carbon; Compounds thereof
- C01B32/50—Carbon dioxide
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
- F25J2200/00—Processes or apparatus using separation by rectification
- F25J2200/02—Processes or apparatus using separation by rectification in a single pressure main column system
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
- F25J2200/00—Processes or apparatus using separation by rectification
- F25J2200/40—Features relating to the provision of boil-up in the bottom of a column
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
- F25J2200/00—Processes or apparatus using separation by rectification
- F25J2200/70—Refluxing the column with a condensed part of the feed stream, i.e. fractionator top is stripped or self-rectified
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
- F25J2210/00—Processes characterised by the type or other details of the feed stream
- F25J2210/04—Mixing or blending of fluids with the feed stream
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
- F25J2210/00—Processes characterised by the type or other details of the feed stream
- F25J2210/70—Flue or combustion exhaust gas
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
- F25J2215/00—Processes characterised by the type or other details of the product stream
- F25J2215/04—Recovery of liquid products
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
- F25J2215/00—Processes characterised by the type or other details of the product stream
- F25J2215/80—Carbon dioxide
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
- F25J2220/00—Processes or apparatus involving steps for the removal of impurities
- F25J2220/80—Separating impurities from carbon dioxide, e.g. H2O or water-soluble contaminants
- F25J2220/82—Separating low boiling, i.e. more volatile components, e.g. He, H2, CO, Air gases, CH4
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
- F25J2230/00—Processes or apparatus involving steps for increasing the pressure of gaseous process streams
- F25J2230/30—Compression of the feed stream
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
- F25J2245/00—Processes or apparatus involving steps for recycling of process streams
- F25J2245/02—Recycle of a stream in general, e.g. a by-pass stream
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
- F25J2270/00—Refrigeration techniques used
- F25J2270/90—External refrigeration, e.g. conventional closed-loop mechanical refrigeration unit using Freon or NH3, unspecified external refrigeration
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02C—CAPTURE, STORAGE, SEQUESTRATION OR DISPOSAL OF GREENHOUSE GASES [GHG]
- Y02C20/00—Capture or disposal of greenhouse gases
- Y02C20/40—Capture or disposal of greenhouse gases of CO2
Abstract
Low pressure CO to which the invention relates 2 The low-temp gas separating process and apparatus features use of raw gas for pressurizing and afterheat utilization, and CO 2 Initial cooling, CO 2 The steps of deep condensation liquefaction, product separation and purification and tower top gas recycling are completed, and the method comprises a raw material gas compressor and CO 2 Initial cooler, reboiler, the deep condensation liquefier at the bottom of the tower and stripping tower, overhead gas throttle condenser and top of the tower gas separator, through this scheme, the feed gas pressure boost is accomplished through one-level compression, and the required cold volume of overhead gas throttle condenser is provided by the medium, has reduced the energy consumption, has reduced the use of ammonia, CO 2 The initial cooler adopts a three-flow plate-fin heat exchanger, optimizes a heat exchange network, improves heat exchange efficiency, adopts a stripping tower for purification, cancels tower top reflux, simplifies a self-control system of the tower, adopts a built-in plate-fin heat exchanger as a tower bottom reboiler, and realizes CO by using a feed gas compressor 2 Tower topThe recycling of gas improves the utilization rate of equipment and CO 2 And (4) recovering rate.
Description
Technical Field
The invention relates to a gas separation technology, in particular to low-pressure CO 2 A low-temperature gas separation method and device.
Background
CO in the atmosphere 2 The concentration rise has a profound influence on the human society and the natural environment, and a plurality of serious disasters are closely related to the concentration rise, so that the CO is reduced 2 Is a problem associated with the continuous development of human society, and thus has received wide attention from countries throughout the world.
And CO 2 The emission mainly comes from the combustion of fossil fuel, is restricted by various factors, the global energy structure mainly based on fossil fuel can not be fundamentally changed in the near future, and the carbon capture utilization and sequestration technology (CCUS) is to reduce the emission of CO into the atmosphere under the condition of not reducing the use amount of the current fossil fuel 2 Means for measuring the amount of gas. The technology is one of the most important emission reduction technologies for ensuring the leading position of world clean energy in advanced countries such as English, American and Japan to actively deal with climate change at present. China also determines the technology as a key emission reduction technology. Currently, the related CCUS engineering is not commercially applied. The carbon capture project has high cost, high energy consumption and difficult economic benefit generation, and becomes a root cause for restricting the development of the carbon capture project. Therefore, CO has the most promising industrial application prospect 2 The low-temperature separation process and the device have important significance in energy-saving optimization research.
In recent years, though for thisThe research of the process forms certain results, but all have certain defects, namely CO 2 The recovery rate is low, and the energy consumption of unit products is high; or the process flow is complex, and the number of equipment is large; or the ammonia consumption is more, the leakage risk is increased, and the potential safety hazard is higher.
In summary, the current processes and devices cannot achieve the balance of low energy consumption, high yield, simple flow and high safety.
Disclosure of Invention
In view of the above, the main object of the present invention is to provide a low pressure CO 2 The gas low-temperature separation method and the device have the advantages that the pressurization of the raw material gas is completed through the first-stage compression, the cold quantity required by the condensation of the overhead gas and the heat quantity required by the system are both provided by the medium, the energy consumption is reduced, the use of ammonia is reduced, and CO is used 2 The initial cooler adopts a plate-fin heat exchanger, so that a heat exchange network is optimized, the heat exchange efficiency is improved, the product is purified by adopting a stripping tower, the top reflux of the tower is cancelled, the automatic control system of the tower is simplified, and the built-in plate-fin heat exchanger is adopted as a reboiler at the bottom of the tower. Realizes CO by utilizing a feed gas compressor 2 The cyclic utilization of the tower top gas improves the equipment utilization rate and CO 2 Recovery of CO 2 The recovery rate can be improved by more than 12%.
The invention provides low-pressure CO 2 A cryogenic gas separation process comprising the steps of:
A. raw material gas pressurization and waste heat utilization: CO meeting water content requirements 2 The pressure of the raw material gas is 0.2MPa to 1.0MPa, the temperature is 5 ℃ to 40 ℃, and the raw material gas is pressurized to 2.5MPa to 4.0MPa by a raw material gas compressor, and the temperature is 70 ℃ to 85 ℃; then enters a reboiler at the bottom of the tower to provide heat for a purification system, and simultaneously the temperature of the feed gas is reduced to 21.6-35.5 ℃;
B.CO 2 initial cooling: feeding the raw material gas obtained in the step A and coming out of the tower bottom reboiler into CO 2 The initial cooler is primarily cooled to 12.3-25.5 ℃ after exchanging heat with two cold material flows from the top gas throttling condenser and the top gas separator;
C.CO 2 deep condensation liquefaction: the initial cooled raw material gas enters CO 2 Deep condensing liquefier, further cooling to-10 deg.C to-20 deg.C to condense more than 85% of raw gas into liquid, CO 2 The cold energy required by the deep condensation liquefier is provided by the ammonia refrigerating unit through liquid ammonia circulation, and CO is cooled 2 Returning the formed gas ammonia to the ammonia refrigerating unit;
D. and (3) separating and purifying products: c, deeply condensing and liquefying the obtained CO 2 Separating and purifying in a stripping tower to obtain CO 2 Liquid CO with purity of more than 99% 2 A product;
E. and (3) recycling the gas at the top of the tower: the overhead gas of the stripping tower is cooled to-32 ℃ by an overhead gas throttling condenser and then enters a tower top gas separator, and CO in the separated liquid phase 2 The content can reach 92 percent, then the temperature is reduced to-62 ℃ by throttling, the temperature is increased to-31 ℃ after the heat exchange between the tower top gas throttling condenser and the stripping tower top gas, and then the CO is added 2 The initial cooler exchanges heat with the raw material gas obtained in the step A and discharged from the tower bottom reboiler, further recovers cold, heats up to 15-25 ℃, enters a raw material gas compressor, is mixed with the raw material gas and enters a subsequent flow, and therefore CO is improved 2 Recovery rate of (a); the gas phase of the gas separator at the top of the tower contains CO 2 About 45 percent of hydrocarbon gas, 55 percent of hydrocarbon gas, reducing the pressure and the temperature to about-65 ℃ through throttling, and entering CO 2 The temperature of the initial cooler is raised to 15-25 ℃ after cold energy recovery, and the initial cooler enters a fuel system in the station to realize the recovery and the reutilization of fuel gas resources.
As a further technical scheme, the raw material gas fed into the device in the step A requires CO 2 In an amount of>75% water content<200ppm。
As a further technical scheme, the raw material gas pressurization in the step A adopts first-stage compression.
The invention provides low-pressure CO 2 The low-temperature gas separator includes material gas compressor and CO 2 Initial cooler and tower reboiler, feeding device CO meeting water content requirement 2 The raw material gas enters the input end of a raw material gas compressor, the output end of the raw material gas compressor is connected with the input end of a tower bottom reboiler, and the output end of the tower bottom reboiler is connected with liquid CO 2 The external transportation pipeline is connected.
As a further technical scheme, the method also comprises CO 2 A deep condensation liquefier and a stripping tower, a tower bottom reboiler is arranged at the bottom in the stripping tower, and the output end of the tower bottom reboiler passes through CO 2 After initial cooler with CO 2 The input end of the deep condensation liquefier is connected with CO 2 The output end of the deep condensation liquefier is connected with the input end of the stripping tower, and the liquid phase output end of the stripping tower is connected with the liquid CO 2 The external transportation pipeline is connected.
As a further technical scheme, the device also comprises a tower top gas throttling condenser and a tower top gas separator, wherein the gas phase output end of the stripping tower is connected with the shell pass input end of the tower top gas throttling condenser, the shell pass output end of the tower top gas throttling condenser is connected with the input end of the tower top gas separator, the liquid phase output end of the tower top gas separator is connected with the tube pass input end of the tower top gas throttling condenser, and the tube pass output end of the tower top gas throttling condenser passes through CO 2 The initial cooler is connected with the input end of the raw material gas compressor, and the gas phase output end of the gas separator at the top of the tower passes through CO 2 The primary cooler is connected to the fuel gas system.
As a further technical scheme, the feed gas compressor is a screw compressor;
as a further technical solution, the CO is 2 The initial cooler is a three-flow plate-fin heat exchanger.
As a further technical scheme, the reboiler at the tower bottom is a built-in plate-fin heat exchanger.
As a further technical solution, the CO is 2 Liquid ammonia inlet and CO of deep condensation liquefier 2 And a gas ammonia outlet of the deep condensation liquefier is respectively connected with a liquid ammonia circulating pipeline of the refrigerating unit.
The beneficial effect after adopting above-mentioned technical scheme is: low-pressure CO 2 The gas low-temperature separation method and the device have the advantages that the pressurization of the raw material gas is completed through the first-stage compression, the cold quantity required by the condensation of the overhead gas and the heat quantity required by the system are both provided by the medium, the energy consumption is reduced, the use of ammonia is reduced, and CO is used 2 The initial cooler adopts a plate-fin heat exchanger, so that a heat exchange network is optimized, the heat exchange efficiency is improved, the product purification adopts a stripping tower, and the tower top return is cancelledThe flow simplifies the automatic control system of the tower, adopts the built-in plate-fin heat exchanger as a reboiler at the bottom of the tower, reduces the occupied space and improves the heat exchange effect. Realizes CO by utilizing a feed gas compressor 2 The cyclic utilization of the tower top gas saves the arrangement of a tower top gas compressor, and improves the equipment utilization rate and CO 2 Recovery of CO 2 The recovery rate can be improved by more than 12%.
Drawings
Fig. 1 is a schematic view of the overall connection structure of the present invention.
In the figure, 1-raw material gas compressor, 2-tower bottom reboiler and 3-CO 2 Initial cooler, 4-CO 2 The system comprises a deep condensation liquefier, a 5-stripping tower, a 6-overhead gas throttling condenser, a 7-overhead gas separator and an 8-liquid ammonia circulation pipeline.
Detailed Description
Specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.
As shown in FIG. 1, the present invention relates to low pressure CO 2 A cryogenic gas separation process comprising the steps of:
A. raw material gas pressurization and waste heat utilization: CO meeting water content requirements 2 The pressure of the raw material gas is 0.2MPa to 1.0MPa, the temperature is 5 ℃ to 40 ℃, and the raw material gas is pressurized to 3.5MPa by a raw material gas compressor 1, and the temperature is 80 ℃; then, heat is provided for a purification system through a tower bottom reboiler 2, and simultaneously the temperature of feed gas is reduced to 30 ℃;
B.CO 2 initial cooling: feeding the raw material gas obtained in the step A and coming out of the tower bottom reboiler into CO 2 The initial cooler 3 exchanges heat with two cold streams from an overhead gas throttling condenser 6 and an overhead gas separator 7 and then is initially cooled to 12.3-25.5 ℃;
C.CO 2 deep condensation liquefaction: the initial cooled raw material gas enters CO 2 Deep condensing liquefier 4, further cooling to-10 deg.C to condense over 85% of the raw gas into liquid, CO 2 The cold quantity required by the deep condensation liquefier 4 is provided by the ammonia refrigerating unit through liquid ammonia circulation, and CO is cooled 2 Returning the formed gas ammonia to the ammonia refrigerating unit;
D.and (3) separating and purifying products: c, deeply condensing and liquefying the obtained CO 2 Separating and purifying in a stripping tower 5 to obtain CO 2 Liquid CO with purity of more than 99% 2 Producing a product;
E. and (3) recycling the gas at the top of the tower: the overhead gas of the stripping tower 5 is cooled to-32 ℃ by a tower overhead gas throttling condenser and then enters a tower overhead gas separator 7, and CO in the separated liquid phase 2 The content can reach 92 percent, then the temperature is reduced to-62 ℃ by throttling, the temperature is increased to-31 ℃ after the heat exchange between the tower top gas throttling condenser 6 and the stripping tower top gas, and then the CO is added 2 The initial cooler 3 exchanges heat with the raw material gas obtained in the step A and discharged from the tower bottom reboiler 2 to further recover cold energy, the temperature is raised to 15-25 ℃, the raw material gas enters the raw material gas compressor 1 to be mixed with the raw material gas and then enters the subsequent flow, and therefore CO is improved 2 Recovery rate of (a); the gas phase of the overhead gas separator 7 contains CO 2 About 45 percent of hydrocarbon gas, 55 percent of hydrocarbon gas, reducing the pressure and the temperature to about-65 ℃ through throttling, and entering CO 2 The temperature of the initial cooler 3 rises to 15-25 ℃ after cold energy recovery, and the initial cooler enters a fuel system in the station to realize the recovery and the reutilization of fuel gas resources.
As a further example, the feed gas to the unit in step A may require CO 2 In an amount of>75% water content<200ppm。
As a further example, the raw material gas pressurization in the step A adopts first-stage compression;
low pressure CO to which the invention relates 2 The low-temperature gas separator comprises a raw gas compressor 1 and CO 2 An initial cooler 3 and a tower bottom reboiler 2, and a device CO feeding device meeting the water content requirement 2 The raw material gas is connected with the input end of a raw material gas compressor 1, the output end of the raw material gas compressor 1 is connected with the input end of a tower bottom reboiler 2, and the output end of the tower bottom reboiler 2 is connected with liquid CO 2 The external transportation pipeline is connected.
As a further embodiment, CO is also included 2 A deep condensation liquefier 4 and a stripping tower 5, a tower bottom reboiler 2 is arranged at the bottom in the stripping tower 5, and the output end of the tower bottom reboiler 2 passes through CO 2 After the initial cooler 3 with CO 2 The input end of the deep condensation liquefier 4 is connected with CO 2 Deep condensateThe output end of the vaporizer 4 is connected with the input end of the stripping tower 5, and the liquid phase output end of the stripping tower 5 is connected with the liquid CO 2 The external transportation pipeline is connected.
As a further embodiment, the system also comprises a top gas throttling condenser 6 and an overhead gas separator 7, wherein the gas phase output end of the stripping tower 5 is connected with the shell pass input end of the top gas throttling condenser 6, the shell pass output end of the top gas throttling condenser 6 is connected with the input end of the overhead gas separator 7, the liquid phase output end of the overhead gas separator 7 is connected with the tube pass input end of the top gas throttling condenser 6, and the tube pass output end of the top gas throttling condenser 6 passes through CO 2 The initial cooler 3 is connected with the input end of the raw material gas compressor 1, and the gas phase output end of the tower top gas separator 7 passes through CO 2 The initial cooler 3 is connected to the fuel gas system.
As a further example, the feed gas compressor 1 is a screw compressor;
as a further example, the CO is 2 The initial cooler 3 is a three-stream plate-fin heat exchanger.
As a further example, the bottom reboiler 2 is a built-in plate fin heat exchanger.
As a further example, the CO is 2 Liquid ammonia inlet and CO of deep condensation liquefier 4 2 And a gas ammonia outlet of the deep condensation liquefier 4 is respectively connected with a liquid ammonia circulating pipeline 8 of the refrigerating unit.
Application of the Low pressure CO of the invention in the above examples 2 The technical scheme of low-temperature gas separation method and device, especially for low-pressure gas and CO as raw material gas 2 In an amount of>75% of scenes.
1) The pressurization of the feed gas compressor 1 is completed by one-stage compression, so that the equipment composition is simplified;
2) the heat used by the separation and purification part and the cold required by the overhead gas throttling condenser 6 are both provided by the medium, so that the energy consumption is reduced, the use and distribution of ammonia are reduced, and the safety of the device is greatly improved;
3)CO 2 the initial cooler 3 adopts a three-flow plate-fin heat exchanger, so that a heat exchange network is optimized, and the heat exchange efficiency is improved;
4) the tower bottom reboiler 2 is arranged at the bottom in the stripping tower 5 by adopting a built-in plate-fin heat exchanger, so that the occupied space is reduced, and the heat exchange effect is improved;
5) the separation and purification cancels the reflux of the tower top, thereby reducing the complexity of a control system;
6) realizes CO by utilizing the feed gas compressor 1 2 The cyclic utilization of the tower top gas saves the arrangement of a tower top gas compressor, and improves the equipment utilization rate and CO 2 And (4) recovering rate.
According to the technical scheme of the invention, detection data in practical application are as follows:
| item | Quantity and name |
| CO 2 Recovery amount | 5783kg/h |
| CO 2 Recovery rate | 92.51％ |
| CO 2 Purity of the product | Over 99 percent |
| Partial energy consumption of pressure boost | 0.218MJ/kg.CO 2 |
| Energy consumption of separation and liquefaction part | 0.179MJ/kg.CO 2 |
| Purification part energy consumption | 0 |
| CO 2 Energy consumption recovery | 0.397MJ/kg.CO 2 |
The above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. The scope of the present invention is defined by the claims.
Claims (10)
1. Low-pressure CO 2 The low-temperature gas separation method is characterized by comprising the following steps of:
A. raw material gas pressurization and waste heat utilization: CO meeting water content requirements 2 The pressure of the raw material gas is 0.2MPa to 1.0MPa, the temperature is 5 ℃ to 40 ℃, and the raw material gas is pressurized to 2.5MPa to 4.0MPa by a raw material gas compressor, and the temperature is 70 ℃ to 85 ℃; then enters a reboiler at the bottom of the tower to provide heat for a purification system, and simultaneously the temperature of the feed gas is reduced to 21.6-35.5 ℃;
B.CO 2 initial cooling: feeding the raw material gas obtained in the step A and coming out of the tower bottom reboiler into CO 2 The initial cooler is primarily cooled to 12.3-25.5 ℃ after exchanging heat with two cold material flows from the top gas throttling condenser and the top gas separator;
C.CO 2 deep condensation liquefaction: the initial cooled raw material gas enters CO 2 Deep condensing liquefier, further cooling to-10 deg.C to-20 deg.C to condense more than 85% of raw gas into liquid, CO 2 The cold energy required by the deep condensation liquefier is provided by the ammonia refrigerating unit through liquid ammonia circulation, and CO is cooled 2 Returning the formed gas ammonia to the ammonia refrigerating unit;
D. and (3) separating and purifying products: c, deeply condensing and liquefying the obtained CO 2 Separating and purifying in a stripping tower to obtain CO 2 Liquid CO with purity of more than 99% 2 Producing a product;
E. and (3) recycling the gas at the top of the tower: the top gas of the stripping tower is cooled to-32 ℃ by a tower top gas throttling condenser and then enters the tower top gas for separationA reactor, CO in the separated liquid phase 2 The content can reach 92 percent, then the temperature is reduced to-62 ℃ by throttling, the temperature is increased to-31 ℃ after the heat exchange between the tower top gas throttling condenser and the stripping tower top gas, and then the CO is added 2 The initial cooler exchanges heat with the raw material gas obtained in the step A and discharged from the tower bottom reboiler, further recovers cold, heats up to 15-25 ℃, enters a raw material gas compressor, is mixed with the raw material gas and enters a subsequent flow, and therefore CO is improved 2 Recovery rate of (a); the gas phase of the gas separator at the top of the tower contains CO 2 About 45 percent of hydrocarbon gas, 55 percent of hydrocarbon gas, reducing the pressure and the temperature to about-65 ℃ through throttling, and entering CO 2 The temperature of the initial cooler is raised to 15-25 ℃ after cold energy recovery, and the initial cooler enters a fuel system in the station to realize the recovery and the reutilization of fuel gas resources.
2. Low pressure CO according to claim 1 2 The low-temperature gas separation method is characterized in that the raw material gas fed into the device in the step A requires CO 2 In an amount of>75% water content<200ppm。
3. Low pressure CO according to claim 1 2 The low-temperature gas separation method is characterized in that the raw material gas pressurization in the step A adopts first-stage compression.
4. Low-pressure CO 2 The low-temperature gas separation device is characterized by comprising a raw gas compressor and CO 2 Initial cooler, tower bottom reboiler, and feeding device CO meeting water content requirement 2 The raw material gas enters the input end of a raw material gas compressor, the output end of the raw material gas compressor is connected with the input end of a tower bottom reboiler, and the output end of the tower bottom reboiler passes through CO 2 After heat exchange with liquid CO in the initial cooler 2 The external transportation pipeline is connected.
5. Low pressure CO according to claim 4 2 The gas low-temperature separation device is characterized by also comprising CO 2 A deep condensation liquefier and a stripping tower, a tower bottom reboiler is arranged at the bottom in the stripping tower, and the output end of the tower bottom reboiler passes through CO 2 Initial coolerPost-reaction with CO 2 The input end of the deep condensation liquefier is connected with CO 2 The output end of the deep condensation liquefier is connected with the input end of the stripping tower, and the liquid phase output end of the stripping tower is connected with the liquid CO 2 The external transportation pipeline is connected.
6. Low pressure CO according to claim 4 or 5 2 The low-temperature gas separation device is characterized by further comprising a top gas throttling condenser and a top gas separator, wherein the gas phase output end of the stripping tower is connected with the shell pass input end of the top gas throttling condenser, the shell pass output end of the top gas throttling condenser is connected with the input end of the top gas separator, the liquid phase output end of the top gas separator is connected with the tube pass input end of the top gas throttling condenser, and the tube pass output end of the top gas throttling condenser passes through CO 2 The initial cooler is connected with the input end of the raw material gas compressor, and the gas phase output end of the gas separator at the top of the tower passes through CO 2 The primary cooler is connected to the fuel gas system.
7. Low pressure CO according to claim 4 2 The low-temperature gas separation device is characterized in that the feed gas compressor is a screw compressor.
8. Low pressure CO according to claim 4 2 Cryogenic gas separation plant, characterized in that said CO is 2 The initial cooler is a three-flow plate-fin heat exchanger.
9. Low pressure CO according to claim 4 2 The low-temperature gas separation device is characterized in that the reboiler at the bottom of the tower is a built-in plate-fin heat exchanger.
10. Low pressure CO according to claim 6 2 Cryogenic gas separation plant, characterized in that said CO is 2 Liquid ammonia inlet and CO of deep condensation liquefier 2 And the gas ammonia outlet of the deep condensation liquefier is respectively connected with a liquid ammonia circulating pipeline of the refrigerating unit.
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| CN114963691B (en) | 2023-12-26 |
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